The present invention relates to earthquake safety devices, and more particularly to devices which close a valve and actuate a micro switch as a result of an earthquake.
There is world wide concern regarding the effects of earthquakes. In recent years, earthquakes occurring around the world resulted in tens of thousands of deaths. Although modern building codes drastically reduce the human harm resulting from earthquakes, there is still a significant likelihood that deaths will occur even in modern countries. Although building codes have been successful in reducing the catastrophic collapse of structures, there is often substantial secondary damage resulting from gas fires, broken electrical wiring, and the like. Various devices have been developed to turn off gas lines and the like, either directly through a mechanical action, or indirectly through actuation of an electrical switch.
One such device is described in U.S. Pat. No. 4,185,507 for “Acceleration Responsive Tripping Mechanism,” which describes a ball sitting on a pedestal. When motion occurs, the ball falls off the pedestal into a surrounding chamber (or dish), causing the chamber to lower against a spring, and to trip a micro switch. Disadvantageously, the device of the '507 patent includes a number of moving parts including a spring, vertically moving piston, and levers. Devices such as this are generally mounted, and forgotten. There is typically little to no inspection or maintenance, and as a result, such complexity is an invitation to failure.
U.S. Pat. No. 4,261,379 for “Vibration/Temperature Sensitive Valve Operating Apparatus,” describes a ball siting in a cup. Motion causes the ball to fall out of the cup, and the cup raises slightly, this motion releases a trigger which results in the desired actuation. Unfortunately the '379 patent also includes substantial mechanical complexity, including several arms, springs, and pins. Such mechanical complexity is undesirable for the reasons cited above.
A simple device for directly turning off a gas flow is described by U.S. Pat. No. 5,209,454 for “Automatic Safety Shutoff Valve,” which is assigned the inventor of the present invention. The '454 patent describes several embodiments of a flapper-type gas valve which closes when experiencing the accelerations characteristic of an earthquake. While the valve of the '454 patent provides the desired gas shut-off functionality, in some applications there is an additional need for a valve which both shuts off a gas flow, and provides an electrical signal for an alarm or monitor.